AMDGPU: Fix crash when MachinePointerInfo invalid

[arsenm]

Summary

The combine on a select of a load only triggers for
addrspace 0, and discards the MachinePointerInfo. The
conservative default needs to be used for this.

[msearles]

LGTM

[arsenm]

r328652

lib/Target/AMDGPU/SIISelLowering.cpp

bool SITargetLowering::isNoopAddrSpaceCast(unsigned SrcAS,
                                            unsigned DestAS) const {
   return isFlatGlobalAddrSpace(SrcAS, AMDGPUASI) &&
          isFlatGlobalAddrSpace(DestAS, AMDGPUASI);
 }
 
 bool SITargetLowering::isMemOpHasNoClobberedMemOperand(const SDNode *N) const {
   const MemSDNode *MemNode = cast<MemSDNode>(N);
   const Value *Ptr = MemNode->getMemOperand()->getValue();
-  const Instruction *I = dyn_cast<Instruction>(Ptr);
+  const Instruction *I = dyn_cast_or_null<Instruction>(Ptr);
   return I && I->getMetadata("amdgpu.noclobber");
 }
 
 bool SITargetLowering::isCheapAddrSpaceCast(unsigned SrcAS,
                                             unsigned DestAS) const {
   // Flat -> private/local is a simple truncate.
   // Flat -> global is no-op
   if (SrcAS == AMDGPUASI.FLAT_ADDRESS)

test/CodeGen/AMDGPU/load-select-ptr.ll

+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=fiji -verify-machineinstrs < %s | FileCheck -check-prefix=GCN %s
+
+; Combine on select c, (load x), (load y) -> load (select c, x, y)
+; drops MachinePointerInfo, so it can't be relied on for correctness.
+
+; GCN-LABEL: {{^}}select_ptr_crash_i64_flat:
+; GCN: s_load_dwordx2
+; GCN: s_load_dwordx2
+; GCN: s_load_dwordx2
+
+; GCN: v_cmp_eq_u32
+; GCN: v_cndmask_b32
+; GCN: v_cndmask_b32
+
+; GCN-NOT: load_dword
+; GCN: flat_load_dwordx2
+; GCN-NOT: load_dword
+
+; GCN: flat_store_dwordx2
+define amdgpu_kernel void @select_ptr_crash_i64_flat(i32 %tmp, i64* %ptr0, i64* %ptr1, i64 addrspace(1)* %ptr2) {
+  %tmp2 = icmp eq i32 %tmp, 0
+  %tmp3 = load i64, i64* %ptr0, align 8
+  %tmp4 = load i64, i64* %ptr1, align 8
+  %tmp5 = select i1 %tmp2, i64 %tmp3, i64 %tmp4
+  store i64 %tmp5, i64 addrspace(1)* %ptr2, align 8
+  ret void
+}
+
+; The transform currently doesn't happen for non-addrspace 0, but it
+; should.
+
+; GCN-LABEL: {{^}}select_ptr_crash_i64_global:
+; GCN: s_load_dwordx2
+; GCN: s_load_dwordx2
+; GCN: s_load_dwordx2
+; GCN: s_load_dwordx2 s{{\[[0-9]+:[0-9]+\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0x0{{$}}
+; GCN: s_load_dwordx2 s{{\[[0-9]+:[0-9]+\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0x0{{$}}
+; GCN: v_cndmask_b32
+; GCN: v_cndmask_b32
+; GCN: flat_store_dwordx2
+define amdgpu_kernel void @select_ptr_crash_i64_global(i32 %tmp, i64 addrspace(1)* %ptr0, i64 addrspace(1)* %ptr1, i64 addrspace(1)* %ptr2) {
+  %tmp2 = icmp eq i32 %tmp, 0
+  %tmp3 = load i64, i64 addrspace(1)* %ptr0, align 8
+  %tmp4 = load i64, i64 addrspace(1)* %ptr1, align 8
+  %tmp5 = select i1 %tmp2, i64 %tmp3, i64 %tmp4
+  store i64 %tmp5, i64 addrspace(1)* %ptr2, align 8
+  ret void
+}
+
+; GCN-LABEL: {{^}}select_ptr_crash_i64_local:
+; GCN: ds_read_b64
+; GCN: ds_read_b64
+; GCN: v_cndmask_b32
+; GCN: v_cndmask_b32
+; GCN: flat_store_dwordx2
+define amdgpu_kernel void @select_ptr_crash_i64_local(i32 %tmp, i64 addrspace(3)* %ptr0, i64 addrspace(3)* %ptr1, i64 addrspace(1)* %ptr2) {
+  %tmp2 = icmp eq i32 %tmp, 0
+  %tmp3 = load i64, i64 addrspace(3)* %ptr0, align 8
+  %tmp4 = load i64, i64 addrspace(3)* %ptr1, align 8
+  %tmp5 = select i1 %tmp2, i64 %tmp3, i64 %tmp4
+  store i64 %tmp5, i64 addrspace(1)* %ptr2, align 8
+  ret void
+}
+
+; The transform will break addressing mode matching, so unclear it
+; would be good to do
+
+; GCN-LABEL: {{^}}select_ptr_crash_i64_local_offsets:
+; GCN: ds_read_b64 {{v\[[0-9]+:[0-9]+\]}}, v{{[0-9]+}} offset:128
+; GCN: ds_read_b64 {{v\[[0-9]+:[0-9]+\]}}, v{{[0-9]+}} offset:512
+; GCN: v_cndmask_b32
+; GCN: v_cndmask_b32
+define amdgpu_kernel void @select_ptr_crash_i64_local_offsets(i32 %tmp, i64 addrspace(3)* %ptr0, i64 addrspace(3)* %ptr1, i64 addrspace(1)* %ptr2) {
+  %tmp2 = icmp eq i32 %tmp, 0
+  %gep0 = getelementptr inbounds i64, i64 addrspace(3)* %ptr0, i64 16
+  %gep1 = getelementptr inbounds i64, i64 addrspace(3)* %ptr1, i64 64
+  %tmp3 = load i64, i64 addrspace(3)* %gep0, align 8
+  %tmp4 = load i64, i64 addrspace(3)* %gep1, align 8
+  %tmp5 = select i1 %tmp2, i64 %tmp3, i64 %tmp4
+  store i64 %tmp5, i64 addrspace(1)* %ptr2, align 8
+  ret void
+}